15 August 2008

Shampoo

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Shampoo is a hair care product used for the removal of oils, dirt, skin particles, dandruff, environmental pollutants and other contaminant particles that gradually build up in hair. The goal is to remove the unwanted build-up without stripping out so much as to make hair unmanageable.

Shampoo, when lathered with water, is a surfactant, which, while cleaning the hair and scalp, can remove the natural oils (sebum) which lubricate the hair shaft.

Shampooing is frequently followed by conditioners which increase the ease of combing and styling.


History

People used to use regular soap to wash their hair.[1] However, the dull film soap left on the hair made it uncomfortable, irritating, and unhealthy looking. According to Shobhana, the word shampoo in English usage dates back to 1762, with the meaning "to massage". The word was a loan from Anglo-Indian shampoo, in turn from Hindi chāmpo , imperative of chāmpnā , "to smear, knead the muscles, massage". It itself comes from Sanskrit/Hindi word "champā" , the flowers of the plant Michelia champaca which have traditionally been used to make fragrant hair-oil.

The term and service was introduced by a Bengali entrepreneur Sake Dean Mahomed, who opened a shampooing bath known as 'Mahomed's Indian Vapour Baths' in Brighton, England in 1759. His baths were like Turkish baths where clients received an Indian treatment of champi (shampooing) or therapeutic massage. His service was appreciated; he received the high accolade of being appointed ‘Shampooing Surgeon’ to both George IV and William IV.

During the early stages of shampoo, English hair stylists boiled shaved soap in water and added herbs to give the hair shine and fragrance. Kasey Hebert was the first known maker of shampoo, and the origin is currently attributed to him.

Originally, soap and shampoo were very similar products; both containing surfactants, a type of detergent. Modern shampoo as it is known today was first introduced in the 1930s with Drene, the first synthetic (non-soap) shampoo.[2]

From ancient times to this day, Indians have been using different formulations of shampoos using herbs like neem, shikakai or soapnut, henna, bael, brahmi, fenugreek, buttermilk, amla, aloe, and almond in combination with some aromatic components like sandalwood, jasmine, turmeric, rose, and musk.


How shampoo works ?

Shampoo cleans by stripping sebum from the hair. Sebum is an oil secreted by hair follicles that is readily absorbed by the strands of hair, and forms a protective layer. Sebum protects the protein structure of hair from damage, but this protection comes at a cost. It tends to collect dirt, styling products and scalp flakes. Surfactants strip the sebum from the hair shafts and thereby remove the dirt attached to it.

While both soaps and shampoos contain surfactants, soap bonds to oils with such affinity that it removes too much if used on hair. Shampoo uses a different class of surfactants balanced to avoid removing too much oil from the hair.

The chemical mechanisms that underlie hair cleansing are similar to that of traditional soap. Undamaged hair has a hydrophobic surface to which skin lipids such as sebum stick, but water is initially repelled. The lipids do not come off easily when the hair is rinsed with plain water. The anionic surfactants substantially reduce the interfacial surface tension and allow for the removal of the sebum from the hair shaft. The non-polar oily materials on the hair shaft are solubilised into the surfactant micelle structures of the shampoo and are removed during rinsing. There is also considerable removal through a surfactant and oil "roll up" effect.


Specialized shampoos

Dandruff

Cosmetic companies have developed shampoos specifically for those who have dandruff. These contain fungicides such as ketoconazole, zinc pyrithione and selenium sulfide which reduce loose dander by killing Malassezia furfur. Coal tar and salicylate derivatives are often used as well.

All-natural

Some companies use "all-natural," "organic," "botanical," or "plant-derived" ingredients (such as plant extracts or oils), combining these additions with one or more typical surfactants. The effectiveness of these organic ingredients is disputed.

Alternative shampoos, sometimes marketed as SLS-free, claim to have fewer harsh chemicals - typically none from the sulfate family. They are sometimes claimed to be gentler on human hair.

Baby

Shampoo for infants and young children is formulated so that it is less irritating and usually less prone to produce a stinging or burning sensation if it were to get into the eyes. This is accomplished by one or more of the following formulation strategies:

1. dilution, in case product comes in contact with eyes after running off the top of the head with minimal further dilution;
2. adjusting pH to that of non-stress tears, approximately 7, which may be a higher pH than that of shampoos which are pH adjusted for skin or hair effects, and lower than that of shampoo made of soap;
3. use of surfactants which, alone or in combination, are less irritating than those used in other shampoos;
4. use of nonionic surfactants of the form of polyethoxylated synthetic glycolipids and/or polyethoxylated synthetic monoglycerides, which surfactants counteract the eye sting of other surfactants without producing the anesthetizing effect of alkyl polyethoxylates or alkylphenol polyethoxylates.

The distinction in 4 above does not completely surmount controversy over the use of shampoo ingredients to mitigate eye sting produced by other ingredients, or of use of the products so formulated.

The considerations in 3 and 4 frequently result in a much greater multiplicity of surfactants being used in individual baby shampoos than in other shampoos, and the detergency and/or foaming of such products may be compromised thereby. The monoanionic sulfonated surfactants and viscosity-increasing or foam stabilizing alkanolamides seen so frequently in other shampoos are much less common in the better baby shampoos.

Animal

Shampoo for animals (such as for dogs or cats) should be formulated especially for them, as their skin has fewer cell layers than human skin. Cats' skin is 2-3 cell layers thick, while dogs' skin is 3-5 layers. Human skin, by contrast, is 10-15 cell layers thick. This is a clear example of why one should never use even something as mild as baby shampoo on a cat, dog, or other pet.

Shampoo intended for animals may contain insecticides or other medications for treatment of skin conditions or parasite infestations such as fleas or mange. These must never be used on humans. It is equally important to note that while some human shampoos may be harmful when used on animals, any haircare products that contain active ingredients/drugs (such as zinc in antidandruff shampoos) are potentially toxic when ingested by animals. Special care must be taken not to use those products on pets. Cats are at particular risk due to their instinctive method of grooming their fur with their tongues.

Solid

Solid shampoos or shampoo bars use as their surfactants soaps and/or other surfactants conveniently formulated as solids. They have the advantage of being spill-proof, and the disadvantage of being slowly applied, needing to be dissolved in use.

Jelly/Gel

Stiff, non-pourable clear gels to be squeezed from a tube were once popular forms of shampoo, and can be produced by increasing a shampoo's viscosity. This type of shampoo cannnot be spilled, but unlike a solid, it can still be lost down the drain by sliding off wet skin or hair. Soap jelly was formely made at home by dissolving sodium soap in hot water before being used for shampooing or other purposes, to avoid the problem of slow application of solids noted above.

Paste/cream

Shampoos in the form of pastes or creams were formerly marketed in jars or tubes. The contents were wet but not completely dissolved. They would apply faster than solids and dissolve quickly. Jar contents were prone to contamination by users and hence had to be very well preserved.

Dry shampoo

Powdered shampoos are designed to work without water. They are typically based on powders such as starch or talc, and are intended to absorb excess sebum from the hair before being brushed out.

Source: From Wikipedia, the free encyclopedia

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